The following disclosure relates to network communication.
In some communication systems, components need to adjust transmission parameters such as data rates or packet sizes during operation. In one possible scenario, a multiplexer that is connected to multiple variable bitrate encoders (e.g., in an MPEG-based video transmission system) may be configured to instruct the encoders to transmit data at a specific rate. For example, a multiplexer that delivers a constant bitrate stream to subscribers can instruct encoders to send at bitrates that correspond to the complexity of the signal that is being encoded, while ensuring that the sum of the individual encoder bitrates is not greater than the constant bitrate that the multiplexer has to provide. In this scenario, it is important that the encoders change transmission parameters when requested to do so such that data transmitted with the changed parameters from the multiple encoders can be multiplexed together. If, for example, one of the encoders did not reduce the bitrate of the encoded data for a frame, more bits might arrive at the multiplexer for the frame than the multiplexer could place in the constant-bitrate output stream. Such systems, in which high-precision synchronization is desirable, typically use a deterministic connection (e.g., a connection with a constant or predictable delay) for communication so that messages can be synchronized using deterministic delays.
Components in a communication system can be connected using a stochastic (non-deterministic) network (e.g., a packet-based network using the internet protocol). A delay between the transmission of a message over a stochastic network and the receipt of the message typically is a random variable, so message synchronization can be difficult. Upper and lower bounds on the delay typically can be determined. For some stochastic networks, the upper bound on delay can be infinite (e.g., a packet can be lost and never arrive at the packet's destination), and for other stochastic networks the upper bound on delay can be finite.